Ensure expression context is available to expression builders

called from field expression widgets

python/gui/qgsfieldexpressionwidget.sip

@@ -49,6 +49,18 @@ class QgsFieldExpressionWidget : QWidget
     //! Returns the currently used layer
     QgsVectorLayer* layer() const;
 
+    //! Callback function for retrieving the expression context for the expression
+    //typedef QgsExpressionContext( *ExpressionContextCallback )( const void* context );
+
+    /** Register callback function for retrieving the expression context for the expression
+     * @param fnGetExpressionContext call back function, will be called when the widget requires
+     * the current expression context
+     * @param context context for callback function
+     * @note added in QGIS 2.12
+     * @note not available in Python bindings
+     */
+    //void registerGetExpressionContextCallback( ExpressionContextCallback fnGetExpressionContext, const void* context );
+
   signals:
     //! the signal is emitted when the currently selected field changes
     void fieldChanged( QString fieldName );

src/app/composer/qgsatlascompositionwidget.cpp

@@ -25,6 +25,18 @@
 #include "qgsexpressionbuilderdialog.h"
 #include "qgscomposermap.h"
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  const QgsComposition* composition = ( const QgsComposition* ) context;
+  if ( !composition )
+  {
+    return QgsExpressionContext();
+  }
+
+  QScopedPointer< QgsExpressionContext > expContext( composition->createExpressionContext() );
+  return QgsExpressionContext( *expContext );
+}
+
 QgsAtlasCompositionWidget::QgsAtlasCompositionWidget( QWidget* parent, QgsComposition* c ):
     QWidget( parent ), mComposition( c )
 {
@@ -42,6 +54,8 @@ QgsAtlasCompositionWidget::QgsAtlasCompositionWidget( QWidget* parent, QgsCompos
   // connect to updates
   connect( &mComposition->atlasComposition(), SIGNAL( parameterChanged() ), this, SLOT( updateGuiElements() ) );
 
+  mPageNameWidget->registerGetExpressionContextCallback( &_getExpressionContext, mComposition );
+
   updateGuiElements();
 }
 

src/app/composer/qgsattributeselectiondialog.cpp

@@ -90,12 +90,26 @@ void QgsComposerColumnAlignmentDelegate::updateEditorGeometry( QWidget* editor,
 
 // QgsComposerColumnSourceDelegate
 
-QgsComposerColumnSourceDelegate::QgsComposerColumnSourceDelegate( QgsVectorLayer* vlayer, QObject* parent ) : QItemDelegate( parent ),
-    mVectorLayer( vlayer )
+QgsComposerColumnSourceDelegate::QgsComposerColumnSourceDelegate( QgsVectorLayer* vlayer, QObject* parent, const QgsComposerObject* composerObject )
+    : QItemDelegate( parent )
+    , mVectorLayer( vlayer )
+    , mComposerObject( composerObject )
 {
 
 }
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  const QgsComposerObject* object = ( const QgsComposerObject* ) context;
+  if ( !object )
+  {
+    return QgsExpressionContext();
+  }
+
+  QScopedPointer< QgsExpressionContext > expContext( object->createExpressionContext() );
+  return QgsExpressionContext( *expContext );
+}
+
 QWidget* QgsComposerColumnSourceDelegate::createEditor( QWidget* parent, const QStyleOptionViewItem& option, const QModelIndex& index ) const
 {
   Q_UNUSED( option );
@@ -103,6 +117,7 @@ QWidget* QgsComposerColumnSourceDelegate::createEditor( QWidget* parent, const Q
 
   QgsFieldExpressionWidget *fieldExpression = new QgsFieldExpressionWidget( parent );
   fieldExpression->setLayer( mVectorLayer );
+  fieldExpression->registerGetExpressionContextCallback( &_getExpressionContext, mComposerObject );
 
   //listen out for field changes
   connect( fieldExpression, SIGNAL( fieldChanged( QString ) ), this, SLOT( commitAndCloseEditor() ) );
@@ -281,7 +296,7 @@ QgsAttributeSelectionDialog::QgsAttributeSelectionDialog( QgsComposerAttributeTa
     mColumnsTableView->setModel( mColumnModel );
     mColumnsTableView->horizontalHeader()->setResizeMode( QHeaderView::Stretch );
 
-    mColumnSourceDelegate = new QgsComposerColumnSourceDelegate( vLayer, mColumnsTableView );
+    mColumnSourceDelegate = new QgsComposerColumnSourceDelegate( vLayer, mColumnsTableView, mComposerTable );
     mColumnsTableView->setItemDelegateForColumn( 0, mColumnSourceDelegate );
     mColumnAlignmentDelegate = new QgsComposerColumnAlignmentDelegate( mColumnsTableView );
     mColumnsTableView->setItemDelegateForColumn( 2, mColumnAlignmentDelegate );
@@ -336,7 +351,7 @@ QgsAttributeSelectionDialog::QgsAttributeSelectionDialog( QgsComposerAttributeTa
     mColumnsTableView->setModel( mColumnModelV1 );
     mColumnsTableView->horizontalHeader()->setResizeMode( QHeaderView::Stretch );
 
-    mColumnSourceDelegate = new QgsComposerColumnSourceDelegate( vLayer, mColumnsTableView );
+    mColumnSourceDelegate = new QgsComposerColumnSourceDelegate( vLayer, mColumnsTableView, mComposerTableV1 );
     mColumnsTableView->setItemDelegateForColumn( 0, mColumnSourceDelegate );
     mColumnAlignmentDelegate = new QgsComposerColumnAlignmentDelegate( mColumnsTableView );
     mColumnsTableView->setItemDelegateForColumn( 2, mColumnAlignmentDelegate );

src/app/composer/qgsattributeselectiondialog.h

@@ -34,6 +34,7 @@ class QgsComposerAttributeTableColumnModelV2;
 class QgsComposerTableSortColumnsProxyModel;
 class QgsComposerTableSortColumnsProxyModelV2;
 class QgsComposerTableAvailableSortProxyModelV2;
+class QgsComposerObject;
 
 // QgsComposerColumnAlignmentDelegate
 
@@ -60,7 +61,7 @@ class QgsComposerColumnSourceDelegate : public QItemDelegate
     Q_OBJECT
 
   public:
-    QgsComposerColumnSourceDelegate( QgsVectorLayer* vlayer, QObject *parent = 0 );
+    QgsComposerColumnSourceDelegate( QgsVectorLayer* vlayer, QObject *parent = 0, const QgsComposerObject* composerObject = 0 );
     QWidget *createEditor( QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index ) const override;
     void setEditorData( QWidget *editor, const QModelIndex &index ) const override;
     void setModelData( QWidget *editor, QAbstractItemModel *model, const QModelIndex &index ) const override;
@@ -69,6 +70,7 @@ class QgsComposerColumnSourceDelegate : public QItemDelegate
     void commitAndCloseEditor();
   private:
     QgsVectorLayer* mVectorLayer;
+    const QgsComposerObject* mComposerObject;
 };
 
 // QgsComposerColumnWidthDelegate

src/app/qgsattributetabledialog.cpp

@@ -61,6 +61,19 @@ class QgsAttributeTableDock : public QDockWidget
     }
 };
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *theLayer, QWidget *parent, Qt::WindowFlags flags )
     : QDialog( parent, flags )
     , mDock( 0 )
@@ -222,6 +235,8 @@ QgsAttributeTableDialog::QgsAttributeTableDialog( QgsVectorLayer *theLayer, QWid
       break;
   }
 
+  mUpdateExpressionText->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
+
   mFieldModel = new QgsFieldModel();
   mFieldModel->setLayer( mLayer );
   mFieldCombo->setModel( mFieldModel );

src/app/qgsdiagramproperties.cpp

@@ -36,11 +36,23 @@
 #include <QMessageBox>
 #include <QSettings>
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer* layer, QWidget* parent )
     : QWidget( parent )
 {
   mLayer = layer;
-
   if ( !layer )
   {
     return;
@@ -55,6 +67,7 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer* layer, QWidget* pare
   connect( mEnableDiagramsCheckBox, SIGNAL( toggled( bool ) ), mDiagramFrame, SLOT( setEnabled( bool ) ) );
 
   mScaleRangeWidget->setMapCanvas( QgisApp::instance()->mapCanvas() );
+  mSizeFieldExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
 
   mBackgroundColorButton->setColorDialogTitle( tr( "Select background color" ) );
   mBackgroundColorButton->setAllowAlpha( true );

src/app/qgslabelinggui.cpp

@@ -38,6 +38,18 @@
 #include <QCheckBox>
 #include <QSettings>
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
 
 QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas, QWidget* parent )
     : QWidget( parent )
@@ -58,6 +70,9 @@ QgsLabelingGui::QgsLabelingGui( QgsVectorLayer* layer, QgsMapCanvas* mapCanvas,
     return;
 
   setupUi( this );
+
+  mFieldExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
+
   mFontSizeUnitWidget->setUnits( QStringList() << tr( "Points" ) << tr( "Map unit" ), 1 );
   mBufferUnitWidget->setUnits( QgsSymbolV2::OutputUnitList() << QgsSymbolV2::MM << QgsSymbolV2::MapUnit );
   mShapeSizeUnitWidget->setUnits( QgsSymbolV2::OutputUnitList() << QgsSymbolV2::MM << QgsSymbolV2::MapUnit );
@@ -872,19 +887,6 @@ void QgsLabelingGui::setDataDefinedProperty( const QgsDataDefinedButton* ddBtn,
   lyr.setDataDefinedProperty( p, map.value( "active" ).toInt(), map.value( "useexpr" ).toInt(), map.value( "expression" ), map.value( "field" ) );
 }
 
-static QgsExpressionContext _getExpressionContext( const void* context )
-{
-  QgsExpressionContext expContext;
-  expContext << QgsExpressionContextUtils::globalScope()
-  << QgsExpressionContextUtils::projectScope();
-
-  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
-  if ( layer )
-    expContext << QgsExpressionContextUtils::layerScope( layer );
-
-  return expContext;
-}
-
 void QgsLabelingGui::populateDataDefinedButtons( QgsPalLayerSettings& s )
 {
   Q_FOREACH ( QgsDataDefinedButton* button, findChildren< QgsDataDefinedButton* >() )

src/app/qgsstatisticalsummarydockwidget.cpp

@@ -38,12 +38,29 @@ QList< QgsStatisticalSummary::Statistic > QgsStatisticalSummaryDockWidget::mDisp
 
 #define MISSING_VALUES -1
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsStatisticalSummaryDockWidget* widget = ( const QgsStatisticalSummaryDockWidget* ) context;
+  if ( widget )
+  {
+    expContext << QgsExpressionContextUtils::layerScope( widget->layer() );
+  }
+
+  return expContext;
+}
+
 QgsStatisticalSummaryDockWidget::QgsStatisticalSummaryDockWidget( QWidget *parent )
     : QDockWidget( parent )
     , mLayer( 0 )
 {
   setupUi( this );
 
+  mFieldExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, this );
+
   mLayerComboBox->setFilters( QgsMapLayerProxyModel::VectorLayer );
   mFieldExpressionWidget->setFilters( QgsFieldProxyModel::Numeric );
 

src/app/qgsstatisticalsummarydockwidget.h

@@ -38,6 +38,11 @@ class APP_EXPORT QgsStatisticalSummaryDockWidget : public QDockWidget, private U
     QgsStatisticalSummaryDockWidget( QWidget *parent = 0 );
     ~QgsStatisticalSummaryDockWidget();
 
+    /** Returns the currently active layer for the widget
+     * @note added in QGIS 2.12
+     */
+    QgsVectorLayer* layer() const { return mLayer; }
+
   public slots:
 
     /** Recalculates the displayed statistics

src/gui/editorwidgets/qgsrelationreferenceconfigdlg.cpp

@@ -22,12 +22,27 @@
 #include "qgsvectorlayer.h"
 #include "qgsexpressionbuilderdialog.h"
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
 
 QgsRelationReferenceConfigDlg::QgsRelationReferenceConfigDlg( QgsVectorLayer* vl, int fieldIdx, QWidget* parent )
     : QgsEditorConfigWidget( vl, fieldIdx, parent )
     , mReferencedLayer( 0 )
 {
   setupUi( this );
+
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, vl );
+
   connect( mComboRelation, SIGNAL( currentIndexChanged( int ) ), this, SLOT( relationChanged( int ) ) );
 
   foreach ( const QgsRelation& relation, vl->referencingRelations( fieldIdx ) )

src/gui/qgsfieldexpressionwidget.cpp

@@ -26,6 +26,8 @@ QgsFieldExpressionWidget::QgsFieldExpressionWidget( QWidget *parent )
     : QWidget( parent )
     , mExpressionDialogTitle( tr( "Expression dialog" ) )
     , mDa( 0 )
+    , mExpressionContextCallback( 0 )
+    , mExpressionContextCallbackContext( 0 )
 {
   QHBoxLayout* layout = new QHBoxLayout( this );
   layout->setContentsMargins( 0, 0, 0, 0 );
@@ -127,6 +129,12 @@ QgsVectorLayer *QgsFieldExpressionWidget::layer() const
   return mFieldProxyModel->sourceFieldModel()->layer();
 }
 
+void QgsFieldExpressionWidget::registerGetExpressionContextCallback( QgsFieldExpressionWidget::ExpressionContextCallback fnGetExpressionContext, const void *context )
+{
+  mExpressionContextCallback = fnGetExpressionContext;
+  mExpressionContextCallbackContext = context;
+}
+
 void QgsFieldExpressionWidget::setLayer( QgsMapLayer *layer )
 {
   QgsVectorLayer* vl = dynamic_cast<QgsVectorLayer*>( layer );
@@ -180,7 +188,9 @@ void QgsFieldExpressionWidget::editExpression()
   QString currentExpression = currentText();
   QgsVectorLayer* vl = layer();
 
-  QgsExpressionBuilderDialog dlg( vl, currentExpression );
+  QgsExpressionContext context = mExpressionContextCallback ? mExpressionContextCallback( mExpressionContextCallbackContext ) : *mExpressionContext;
+
+  QgsExpressionBuilderDialog dlg( vl, currentExpression, this, "generic", context );
   if ( !mDa.isNull() )
   {
     dlg.setGeomCalculator( *mDa );

src/gui/qgsfieldexpressionwidget.h

@@ -88,6 +88,18 @@ class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
     //! Returns the currently used layer
     QgsVectorLayer* layer() const;
 
+    //! Callback function for retrieving the expression context for the expression
+    typedef QgsExpressionContext( *ExpressionContextCallback )( const void* context );
+
+    /** Register callback function for retrieving the expression context for the expression
+     * @param fnGetExpressionContext call back function, will be called when the widget requires
+     * the current expression context
+     * @param context context for callback function
+     * @note added in QGIS 2.12
+     * @note not available in Python bindings
+     */
+    void registerGetExpressionContextCallback( ExpressionContextCallback fnGetExpressionContext, const void* context );
+
   signals:
     //! the signal is emitted when the currently selected field changes
     void fieldChanged( QString fieldName );
@@ -138,6 +150,8 @@ class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
     QString mExpressionDialogTitle;
     QSharedPointer<const QgsDistanceArea> mDa;
     QScopedPointer< QgsExpressionContext > mExpressionContext;
+    ExpressionContextCallback mExpressionContextCallback;
+    const void* mExpressionContextCallbackContext;
 };
 
 #endif // QGSFIELDEXPRESSIONWIDGET_H

src/gui/symbology-ng/qgscategorizedsymbolrendererv2widget.cpp

@@ -370,6 +370,19 @@ QgsRendererV2Widget* QgsCategorizedSymbolRendererV2Widget::create( QgsVectorLaye
   return new QgsCategorizedSymbolRendererV2Widget( layer, style, renderer );
 }
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsCategorizedSymbolRendererV2Widget::QgsCategorizedSymbolRendererV2Widget( QgsVectorLayer* layer, QgsStyleV2* style, QgsFeatureRendererV2* renderer )
     : QgsRendererV2Widget( layer, style )
     , mRenderer( 0 )
@@ -451,6 +464,8 @@ QgsCategorizedSymbolRendererV2Widget::QgsCategorizedSymbolRendererV2Widget( QgsV
   advMenu->addAction( tr( "Symbol levels..." ), this, SLOT( showSymbolLevels() ) );
 
   btnAdvanced->setMenu( advMenu );
+
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, layer );
 }
 
 QgsCategorizedSymbolRendererV2Widget::~QgsCategorizedSymbolRendererV2Widget()

src/gui/symbology-ng/qgsgraduatedsymbolrendererv2widget.cpp

@@ -379,6 +379,19 @@ QgsRendererV2Widget* QgsGraduatedSymbolRendererV2Widget::create( QgsVectorLayer*
   return new QgsGraduatedSymbolRendererV2Widget( layer, style, renderer );
 }
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsGraduatedSymbolRendererV2Widget::QgsGraduatedSymbolRendererV2Widget( QgsVectorLayer* layer, QgsStyleV2* style, QgsFeatureRendererV2* renderer )
     : QgsRendererV2Widget( layer, style )
     , mRenderer( 0 )
@@ -472,6 +485,8 @@ QgsGraduatedSymbolRendererV2Widget::QgsGraduatedSymbolRendererV2Widget( QgsVecto
   mHistogramWidget->setRenderer( mRenderer );
   connect( mHistogramWidget, SIGNAL( rangesModified( bool ) ), this, SLOT( refreshRanges( bool ) ) );
   connect( mExpressionWidget, SIGNAL( fieldChanged( QString ) ), mHistogramWidget, SLOT( setSourceFieldExp( QString ) ) );
+
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
 }
 
 void QgsGraduatedSymbolRendererV2Widget::on_mSizeUnitWidget_changed()

src/gui/symbology-ng/qgsheatmaprendererwidget.cpp

@@ -31,6 +31,19 @@ QgsRendererV2Widget* QgsHeatmapRendererWidget::create( QgsVectorLayer* layer, Qg
   return new QgsHeatmapRendererWidget( layer, style, renderer );
 }
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsHeatmapRendererWidget::QgsHeatmapRendererWidget( QgsVectorLayer* layer, QgsStyleV2* style, QgsFeatureRendererV2* renderer )
     : QgsRendererV2Widget( layer, style )
     , mRenderer( NULL )
@@ -54,6 +67,7 @@ QgsHeatmapRendererWidget::QgsHeatmapRendererWidget( QgsVectorLayer* layer, QgsSt
 
   setupUi( this );
   mRadiusUnitWidget->setUnits( QgsSymbolV2::OutputUnitList() << QgsSymbolV2::MM << QgsSymbolV2::Pixel << QgsSymbolV2::MapUnit );
+  mWeightExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
 
   if ( renderer )
   {

src/gui/symbology-ng/qgssizescalewidget.cpp

@@ -78,6 +78,19 @@ void QgsSizeScaleWidget::setFromSymbol()
   updatePreview();
 }
 
+static QgsExpressionContext _getExpressionContext( const void* context )
+{
+  QgsExpressionContext expContext;
+  expContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+
+  const QgsVectorLayer* layer = ( const QgsVectorLayer* ) context;
+  if ( layer )
+    expContext << QgsExpressionContextUtils::layerScope( layer );
+
+  return expContext;
+}
+
 QgsSizeScaleWidget::QgsSizeScaleWidget( const QgsVectorLayer * layer, const QgsMarkerSymbolV2 * symbol )
     : mSymbol( symbol )
     // we just use the minimumValue and maximumValue from the layer, unfortunately they are
@@ -87,6 +100,8 @@ QgsSizeScaleWidget::QgsSizeScaleWidget( const QgsVectorLayer * layer, const QgsM
   setupUi( this );
   setWindowFlags( Qt::WindowStaysOnTopHint );
 
+  mExpressionWidget->registerGetExpressionContextCallback( &_getExpressionContext, mLayer );
+
   if ( mLayer )
   {
     mLayerTreeLayer = new QgsLayerTreeLayer( mLayer );